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Home > Publications > International Concrete Abstracts Portal
The International Concrete Abstracts Portal is an ACI led collaboration with leading technical organizations from within the international concrete industry and offers the most comprehensive collection of published concrete abstracts.
Showing 1-5 of 20 Abstracts search results
Document:
SP76
Date:
October 1, 1982
Author(s):
Aberdeen Publication
Publication:
Symposium Papers
Volume:
76
Abstract:
SP76 A collection of 19 papers on creep and shrinkage in concrete structures. The papers discuss the effects of creep and shrinkage from the practical standpoint of the designer and offer recent research. Topics include: effects of volume changes, time-dependent slab deflections, predicting long-term prestress losses, creep strains and stress redistribution in reinforced concrete columns, analyzing time-dependent forces in continuous concrete structures, stress redistribution in cable-stayed concrete structures, drying shrinkage of high-strength concrete with superplasticizer, deflection of prestressed concrete beams. The book also includes a report from the ACI Committee on Creep and Shrinkage (209R-82) which reviews the methods for predicting creep, shrinkage and temperature effects in concrete structures. Simplified methods are used to predict the material response and to analyze the structural response under service conditions.
DOI:
10.14359/14128
SP76-19
Dobrosav Jevtic
Creep tests were conducted on a number of concrete specimens. Numerous prestressed concrete beams were tested for determining deflection, relaxation, and failure under long-term loading. Some of the tests are still in progress.
10.14359/6800
SP76-18
Karim W. Nasser and H. M. Marzouk
The present tests were made to measure creep of mass concrete containing fly ash at six different temperatures of 70 to 450 F (21.4 to 232 C). At each temperature three stress levels were applied for over 20 months and they were 750, 1200, and 1500 psi (5.17, 8.27, and 10.34 MPa). The results showed that, in general, creep strains increased with a rise in temperature, and the maximum increase occurred at 450 F (232 C). It was also found that beyond 180 days, creep strains vary linearly with stress-strength ratios at temperatures of 70, 160, 350, and 450 F (21.4, 71, 177, and 232 C). However, at temperatures of 250 and 300 F (121 and 149 C), the strains were non-linear with stress-strength ratios at all ages. Based on the experimental results, a basic expression for creep of mass concrete containing fly ash at high temperature was suggested. Results of previous investigation on the effect of high temperature on the strength and elasticity of concrete con-taining fly ash were used to explain the creep behavior at various temperatures.
10.14359/6799
SP76-17
Osama El-Shafey, Ian J. Jordaan, and Robert E. Loov
A set of measurements of time-dependent deflections of prestressed concrete members in a parking structure is presented. Time-dependent strains for field control specimens from the same concrete batch and subjected to the same environmental conditions as the members are given, together with results from control specimens stored in the laboratory. A comparison of these strains and those determined using CEB-FIP Recommendations and the ACI Committee 209 procedure is shown. The deflection of the members was predicted by means of a step-by-step finite element analysis using the strains from the field control specimens. In the analysis, the fact that the major part of creep is irreversible is recognized. Creep and shrinkage strains predicted using the two code procedures were substantially different from those recorded in the field (up to 2.25 times the recorded values). Part of this discrepancy can be attributed to the influence of the environmental conditions (particularly temperature) on creep and shrinkage strains, but the prediction methods themselves leave room for improvement. In spite of the disagreement between the field strains and those predicted by CEB-FIP Recommendations, the measured deflections were similar to those predicted from measured field control strains and to those predicted from CEB-FIP strains. The ACI Committee 209 procedure slightly overestimates the final deflection.
10.14359/6798
SP76-16
Shigeyoshi Nagataki and Asuo Yonekura
In this paper, drying shrinkage and creep test results of 200 high-strength concrete prismatic specimens with the strength of about 98.0 MPa (14.2 ksi), in which water-cement ratios were reduced to 20% by the use of superplasticizer, were experimentally analyzed and compared with those of normal-strength concrete. The drying shrinkage and creep of concrete specimens having three kinds of curing conditions at manufacture (standard, steam, and high pressure steam curing) were measured in air at 20°C and 50% R.H. and some in water at 20°C. The measurement of these volume change tests was continued for 800 days. Strains of prestressed concrete specimens during high pressure steam curing were also measured.
10.14359/6797
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